BT BB 16b(55) :מדאקדמיה אדבורי אדבריה ומדאדבריה עבד תשובה‏ : since (the biblical verse) placed him first [v. Gen 35:29], (this shows that Ishmael) did indeed give him [i.e. Jacob] precedence, and since he gave him precedence, this shows that he repented
See the entire entry for dbr vb. to lead, to drive